Corrosion resistant centrifugal pump



Dec. 24, 1963 1. F. ZAGAR ETAL 3,115,097

CORROSION RESISTANT CENTRIFUGAL PUMP Filed Aug. 3. 1960 3 Sheets-Sheet 1 FIG.

INVENTORS IRVIN FRANK ZAGAR GEORGE M. WILFLEY ATTORNEY 1386- 24, 1963 F. ZAGAR ETAL CORROSION RESISTANT CENTRIFUGAL PUMP 5 Sheets-Sheet 2 Filed Aug. 3. 1960 FIG. 9

Z 92 INVENTORS IRVIN FRANK zAeAR I GEORGE M. WILFLEY FIG 8 ATTORNEY United States Patent 0 3,1153% CQRRUSH'QEN RESETANT CENTRIFUGAL PUMP irvin Frank Zagar and George M. Wilfley, Denver, Colo., assignors to A. R. Wiliiey and Sons, inn, Denver, (Zola, a corporation of Colorado Filed Aug. 3, 196i), Ser. No. 47,191 3 (filaims. (:Cl. ltl3-ltl3) The present invention relates to corrosion resistant centrifugal pumps and more particularly to pumps wherein the portions of the pump contacting the fluid to be pumped are formed of a material which is very effective in resisting corrosion.

The problem has long existed in the art of providing centrifugal pumps of the general type according to the present invention which can effectively pump acids and other materials which have a deleterious corrosion effect on metallic pump parts. Accordingly, many efforts have been made to design a centrifugal pump wherein the portions of the pump contacting the pumped fluid may be formed of a material such as ceramic or glass which is corrosion resistant. The difllculty in this respect is the fact that such corrosion resistant materials are diflicult to form and to provide with sufiicient rigidity and strength to resist the stresses and pressures applied thereto during normal pumping operations.

Another factor which has prevented widespread use of corrosion resistant materials such as ceramics is the fact that these types of material have a high coeflicient of friction. Accordingly, where conventional rubbing contact seals are employed in cooperation with the corrosion resistant parts, excessive heat is generated which requires the provision of a bulky and complex auxiliary cooling system which, of course, is highly undesirable.

It is accordingly a principal object of the present invention to provide a particularly novel arrangement which enables all the components of the pump which contact the corrosive pumped fluid to be formed of corrosion resistant material such as ceramic or glass and the like.

The present invention represents an improvement over US. Patent 2,571,802 to Wilfley et al., wherein a centrifugal pump of the same general type as the present invention is disclosed. The aforementioned patent incorporates an arrangement wherein the drive is transmitted to an impeller shaft through a resilient spring connection, and a centrifugal control means is provided for shifting a shaft axially at predetermined speeds of the shaft. The general concept employed in this type of pump is to eliminate mechanical seals and to rely solely upon a hydraulic seal when the pump is operating. This is accomplished by the fact that the impeller shaft is normally shifted to a mechanically sealing position when the shaft is not rotating, but when the shaft reaches a predetermined speed, the mechanical seal is broken, and a hydraulic seal is relied upon during rotation of the impeller and the impeller shaft. The arrangement as shown in the aforementioned patent has proved to be eminently successful for many years, and this type of hydraulic seal is recognized as being very effective in the art.

Applicants as well as others in the art have for many years attempted to design a centrifugal pump wherein the various components are formed of corrosion resistant material such as ceramic, and the present construction provides an additional combination which readily permits this desired end result. According to the present invention, a centrifugal pump is provided including a hydraulic type seal means which eliminates all friction between the parts formed of corrosion resistant material during pumping operations since there are no mechanical seals, thereby permitting the components to be constructed of such material without the accompanying dis- 3,115,097 Patented Dec. 24, 1963 advantages where mechanical contact seals are employed during pumping operations.

in addition, the particular construction of the present invention provides a very simple, compact and inexpensive construction which permits this type of a pump to be economically manufactured, and at the same time the arrangement provides a high degree of mechanical strength which has generally been lacking in prior art attempts to provide components formed of ceramic material. The present invention provides a housing arrangement surrounding and adjacent to the impeller of the pump wherein the housing arrangement comprises a plurality of interconnected components, each of the components including an outer strong reinforcing armor of hard metallic material with an inner liner formed of corrosion resistant material. In this manner the components are provided with a high degree of mechanical strength and yet effectively resists corrosion during pumping of corrosive fluids. The outer armor layer of each of these components further serves to protect the corrosion re- SlSlElflt material such as ceramic which may be quite brittle and subject to damage if struck by external objects.

The impeller as well as all of the various other components of the pump which contact the fluid also have surfaces formed of similar corrosion resistant material such that the entire pump can resist corrosion over very long periods of time in a manner vastly superior to prior art arrangements. The various components of the present invention which are formed of corrosion resistant material may be formed of a variety of such known materials as ceramics, refractories, vitreous materials, plastics, high silica irons, and other similar materials.

The impeller of the present invention is of a particularly unique construction, and this particular construction has enabled this type of an impeller to be for the first time successfully manufactured completely of a corrosion resistant material in this particular environment. The present invention incorporates a two-chamber type impeller wherein both pumping vanes as well as expeller vanes are incorporated therein. The pumping vanes, of course, provide the primary pumping action which serves to pump the fluid through the apparatus. The expeller vanes are employed for providing an eifective hydraulic seal.

Prior art impellers have generally been of the twochamber, double shrouded closed design type employing conventional curved vane shapes. As a practical matter, this type of construction cannot be made in the corrosion resistant hard-to-form materials as employed in the present invention. As a result, when such corrosion resistant hard-to-form materials have been employed in the prior art, the impellers have been of the single chamber, open or semi-open type which are not nearly so desirable.

Accordingly, one important feature of the present invention is to provide an impeller construction which permits the impeller to be readily formed. In order to provide such a construction, the vanes of the present invention are formed along continuous straight lines, and in other words, the side surfaces of the vanes are substantially fiat which permits ready machining and formation thereof. However, due to the employment of such straightline vanes, an additional problem arises due to the fact that curved vanes are the most efficient type, and that generally speaking, a great deal of efiiciency is lost if straight-line vanes are substituted for curved vanes. This problem is particularly acute in this type of a pump arrangement since the expeller vanes have to work against the head created by the pumping vanes. Since the hydraulic seal depends for its effectiveness upon the efficincy of operation of the expeller vanes, it is necessary to provide an expeller vane arrangement which is highly efficient. This particular problem has been solved in a very effective manner by providing a novel disposition of the straight-line vanes. The pumping vanes as well as the expeller vanes are each disposed such that they are non-radial and that the central longitudinal axes or center lines thereof are offset with respect to the axis of rotation of the impeller. Applicants have found that this particular positioning of the vanes provides good hydraulic efficiency which is almost equal to that of the conventional curved vane arrangement. Accordingly, applicants have obtained the advantages of high hydraulic efficiency along with an arrangement which permits easy forming of the impeller.

Furthermore, since it is extremely dilficult to provide the desired type of corrosion resistant surface on a curved area, the portions of the surrounding housing have been so constructed that the curved areas thereof are at a minimum, thereby providing a straight-line construction throughout the major portions of all of the components of the present apparatus which are constructed of the corrosion resistant material.

An object of the present invention is to provide a new and novel centrifugal pump wherein all the parts which contact the pumped fluid are formed of corrosion resistant material.

Another object of the invention is the provision of a corrosion resistant centrifugal pump which eliminates all friction between the parts formed of corrosion resistant material during a pumping operation.

A further object of the invention is to provide a corrosion resistant centrifugal pump which has a good hydraulic efficiency and wherein the construction is such as to provide a high degree of mechanical strength.

Still another object of the invention is to provide a corrosion resistant centrifugal pump which is quite simple and compact and furthermore, inexpensive in construction.

Other objects and many attendant advantages of the present invention will become more apparent when considercd in connection with the specification and accompanying drawings, wherein:

FIG. 1 is a sectional view of a centrifugal pump according to the present invention;

FIG. 2 is a sectional view illustrating the mode of operation of the governor control means of the present invention;

FIG. 3 is a sectional view illustrating the sealing means in one operative position;

FIG. 4 is a view similar to FIG. 3 illustrating the sealing means in another operative position;

FIG. 5 is a view partly broken away looking at the impeller from the forward end thereof;

FIG. 6 is a view partly broken away looking at the impeller from the rear end thereof;

FIG. 7 is a view taken substantially along line 77 of FIG. 6 looking in the direction of the arrows;

FIG. 8 is an enlarged portion of the structure shown in FIG. 1 of the drawings; and

FIG. 9 is a view partially broken away of a portion of a housing means surrounding the impeller.

Referring now to the drawings wherein like reference characters designate corresponding parts throughout the several views, there is shown in FIG. 1 the general layout of the pump according to the present invention wherein the over all housing is indicated generally by reference numeral 19, this housing consisting of several assemblies which are interconnected with one another to provide the complete assembly for enclosing the various components of the pumping apparatus. The housing has a base structure including a hollow body portion 11, a foot portion 12 which is bolted to the body portion as at 13, and a top portion 14.

The top portion 14 in turn comprises a front bearing portion 15 formed with a vertical flange portion 16 facing forwardly, and a rear bearing portion 17. The top portion 14 of the base structure further constitutes a chamber 18 herein also called the governor chamber extending etween the front and rear bearing portions 15 and 17 respectively and provided with a top plate or cover 19.

The front bearing portion 15 is provided with a front bearing in the form of a ball bearing 2'3 having balls 21, an inner race member 22 and an outer race member 23. This roller bearing is disposed between a front bearing plate 24 having sealing rings 24a and a rear bearing plate 25 having a sealing ring 25a, both bearing plates being held together and in place as by bolts 26. The rear hearing portion 17 is provided with a rear bearing in the form of a ball bearing 27 having balls 28, an inner bearing race 29 and an outer bearing race 39. The ball bearing 27 is held in place and directly confined between a front bearing plate 31 having a sealing ring 32, and a rear bearing plate 33 having a sealing ring 34, both bearing plates being held together and in place as by bolts 35.

A driving sleeve 36 formed with a shoulder 37 is rotatabie in the rear bearing 27 although secured against axial displacement therein as by the shoulder 37 at one side of bearing 27 and an internally threaded stop collar 38 screwed onto the sleeve member 36 at the other side of the bearing 27. The driving sleeve 36 is formed at its inner or forward end with a radial projection or flange portion 39 and has a front bushing 4-0 and a rear bushing 41. In these bushings there is rotatable an impeller shaft 42. These bushings or bearings consist of a known kind of self-lubricating material, for example, specially treated brass or impregnated wood or composition. The impeller shaft is axially shiftable with respect to the driving sleeve 36, the extent of that shift being defined by a certain narrow range or predetermined limits hereinafter further explained.

The front end portion of the impeller shaft 42 is ro- I tatably supported in the front bearing 25} which in turn is bodily shiftable with the shaft 42 relative to the base structure, the bearing 20 being unitary with the shaft by being confined directly between a shoulder 43 formed on shaft 42 and an internally threaded stop collar 44 screwed onto shaft 42. The extent of the potential axial shift of shaft 42 is indicated by the clearance d noted between the bearing 20 and the adjacent bearing plate 25.

The impeller shaft 42 is controllably shifted axially thereof by a control device indicated generally by reference numeral c disposed within the chamber 18 which is in the nature of a centrifugal governor device responsive to the speed of rotation of the impeller shaft. As seen most particularly in FIG. 2 of the drawing, the control device a includes a body means having a portion 50 which is pinned by pin 51 to the shaft 42 and opposite pairs of radially extending lugs 52 are provided for supporting the swingable weight members of the centrifugal device.

A pair of pins 53 are supported between the pairs of lugs 52 at each side of the control device, and the swingable members 54 are pivotally supported thereon. Members 54 each include a weight portion 55 and a foot or cam portion 56 which is adapted to bear against the forward face F of the flange 39 formed at the forward end of the driving sleeve 36.

The driving interconnection between flange portions 60 and 61 are also formed integral with the body means of the speed responsive control device, and the driving connection between fiange 39 fixed to the driving sleeve and flanges 60 and 61 comprises a pair of fiat spring elements 62 and 63 each being of multiple ply construction. These spring elements are fastened to the flange 39 by bolt and nut connections 65, the opposite ends of the spring elements being fastened to the flange portions 60 and 61 of the governor means by bolt and nut connections 66. These spring elements while allowing for a limited but sufficient relative axial movement between the driving sleeve 36 and the impeller shaft 42 also function as torque transmitting elements between the driving sleeve 36 and the impeller sha t 42. It is evident that the springs will urge the impeller shaft toward the light as seen in FIG.- 1 for a purpose hereinafter described.

Referring now to the lefthand portion of FIG. 1, an impeller insert "it? is formed of a corrosion resistant material and is provided with internal threads formed on the longitudinal bore extending therethrough, these internal threads on the insert cooperating with external threads 71 formed at the outermost end of the impeller shaft for securing the impeller insert to the end of the impeller shaft. The insert is knurled and can be keyed or mechanically locked in place. Disposed in surrounding relationship to the outermost portion of the impeller insert 7% and bonded thereto is the impeller of the present invention indicated generally by reference numeral '72, the construction of the impeller being hereinafter more fully described.

A rotary sealing ring '75 is secured in place about the outer surface of impeller insert 7 t), a sealing face 75' being formed on rotary seal ring '75. A gasket 76 is provided between the forward end of the rotary seal ring and the adjacent portion of the impeller. Rotary seal ring '75 is formed of corrosion resistant material of the type previously described.

A shaft sleeve dil is disposed in surrounding relationship and is secured to the impeller shaft 42, sleeve 8%) also being formed of similar corrosion resistant material and having a pair of annular grooves 81 and 3?. formed in the outer surface thereof. A gasket 83 is provided between the forward end of the shaft sleeve S ll and tie adjacent portions of the impeller insert 70 and the rotary seal ring 75. A bracket member 13 is fastened or bonded (the bolts not being shown) to the vertical flange portion 16 of the bearing housing. An impeller housing sub-assembly indicated by letters 111 includes a front plate means indicatcd generally by reference numeral 90), a volute ring means indicated generally by reference numeral 91, and a rear plate means indicated generally by reference numeral 92., these latter three components being clamped together to provide the finished assembly by nut and bolt assemblies @5 which rigidly support the impeller housing sub-assembly from the bracket B.

A stationary seal ring housing 1% is attached as by bolts 1&1 rigidly to the rear plate means 92 such that the seal ring housing does not rotate during operation of the apparatus. Seal ring housing 1% supports a stationary ring seal 1112 at an inner portion thereof, member 102 having an annular sealing face 1il2 formed thereon which is disposed complementary to and adapted to cooperate with the annular sealing face 75 formed on the rotary seal ring 75. Stationary seal ring 1% is also formed of corrosion resistant material.

A pair of annular grooves 163 and 104 are formed in he stationary seal ring housing 1% adjacent to grooves d and 82 formed in shaft sleeve 89, and the surfaces of the grooves 1d?! and as well as the surfaces immediately adjacent to the grooves 1&3 and 1% which contact the fluid during pumping operations are all coated with a suitable corrosion resistant material as described previously. The stationary seal ring housing 1% also includes a downwardly extending spout portion 1645' as seen in F113. 1 which is adapted to direct excess fluid away from the impeller shaft and out of the pump apparatus during pumping operations. In this manner, any pumped fluid which leaks past the hydraulic seal provided by the expeller vanes of the impeller will pass harmlessly outwardly out of the pump apparatus.

Referring now to the novel construction of the impeller housing subassembly, the rear plate means 92 includes an outer member 11h formed of a relatively rigid material such as cast iron, and an inner liner 111 is provided, the inner liner 111 being formed of a suitable corrosion resistant material as hereinbefore discussed. The liner 111 is attached to the outer rigid armor portion 110 by cementing the liner to the outer member by means of Armstrong cement or the like.

It will be noted that liner 111 includes a circumferentially extending groove 112 which serves the function of a labyrinth means in cooperation with a portion of the impeller. The liner is also provided with a relieved portion 113 which tapers inwardly toward the rear portion of the member. The front plate means 96 also comprises an outer member 115 formed of a relatively rigid material such as cast iron and an inner liner 116 is secured to the outer armor portion 115 as by cementing with Armstrong adhesive. lt will be noted that liner 116 is provided with a groove 1241 which serves the function of a labyrinth means in cooperation with a portion of the impeller. The liner 116 is also relieved at portion 121. It will be noted that liner 116 defines a central bore 122 which comprises a forwardly extending suction inlet through which the pumped fluid is drawn into the pump apparatus.

The construction of the volute ring portion 91 will be more evident from a consideration of FIG. 9. This ring portion 91 is formed of two halves which are bolted together by means of bolts 125. The volute ring 91 includes an outer rigid portion 126 which also may be formed of cast iron or the like, and an inner liner 127 is formed of a suitable corrosion resistant material as aforedescribed, the inner liner being held in place by means of a suitable body of cement 123 such as Portland cement. It will be noted that the portion of the liner indicated at 13% is disposed closest to the longitudinal axis 131 of the apparatus, or the rotational axis of the impeller shaft, and that following the inner surface of the liner counterclockwise frorn portion 130, the surface becomes more distant from axis 131 until the portion 132 is reached where the liner is at its maximum distance from the axis 131. The remaining portions of the liner indicated by numerals 133 and 134 define the discharge outlet portion of the pump through which the pumped fluid is discharged. A suitable attaching flange 135 is formed at the upper portion of the outer armor member as seen in FIG. 9.

Referringnow to FIG. 8, an enlarged cross-sectional view is provided illustrating the manner in which the various components 9t), 91 and 92 are nested together in assembled relationship to one another. It will, of course, be recognized that in so far as possible, all the surfaces of the corrosion resistant liners of these components are formed along straight lines or flat surfaces to facilitate forming thereof. However, small curved surfaces may be provided as long as they are of a minor nature. It will be noted that certain curved surfaces are incorporated in the construction of liner 127 as seen in FIG. 8, these small curved areas being provided between certain ofiset portions of the liner 127.

it will be noted that liner 127 includes radially inwardly extending flange portions 14% and 14-1 at the opposite sides thereof, the inner peripheries of these flanges engaging the outer surfaces of shoulders i116 and 113i of the liners 116 and 111 respectively.

An annularly extending recessed portion 14-2 is provided in the inner surface of liner 127, this recess being of a dimension x so as to be of a greater longitudinal extent than the discharge portions of the van-es of the impellers so that the portion of the fluid which is discharged from the vanes of the impellers will be discharged directly into this recessed portion 1452. thereby tending to carry the pumped fluid around and out through the discharge portion of the apparatus. t will also be noted that the outer surface 143 of impeller is spaced radially inwardly of the shoulder portions 16 and 111 formed on the liners 116 and 111 Referring now to FIG. 1, the impeller 7.2 includes a central portion 15 which is, as aforementioned, bonded to the outer surface of the impeller insert The impeller includes a first portion 151 within which the continuous straight line or flat surface pump vanes 152 are formed and a second portion 153 is provided within which the continuous straight line flat surface expeller vanes 154 are formed. It will be noted that portion 153 within which the expeller vanes are formed extends radi- 7 ally outwardly of the portion 251 within which the pumping vanes are formed. Pump vanes 52 and cxpellcr vanes 154 are of substantially similar construction as will hereinafter appear.

A circumferentially extending flange 155 extends forwardly of portion 15d and fits within and is spaced from the walls of the groove 129 formed in liner 116 for providing a labyrinth means therewith. In a like manner, a circumferentially extending flange 159 extends rearwardly of portion 153 of the impeller and tits within and is spaced from the walls of groove 112 fumed in liner 111 for providing a labyrinth means therewith.

It is, of course, clear that fluid entering through the inlet bore 122 will be pumped outwardly by vc. es I152 and thereby caused to move out of the apparatus through the discharge outlet. Varies 154 will also tend to pump out any liquid which may leak by the labyrinth means defined by flange 15S, and groove 112i thereby tending to prevent any liquid from passing toward the rear of the apparatus while the impeller is rotating in its pumping action.

Referring now to FIGS. 5, 6 and 7 of the drawings, the novel disposition of the vanes of the impeller is illustrated, and as seen in FIG. 5, four identical pumping vanes 152 are provided, these vanes extending from the inner annular surface 161 of the impeller to the outer annular surface 162 of the impeller, the opposite ends of the vanes being open as is well understood. The pumping vanes include substan ally flat side surfaces 152 and end surfaces 152 which define pumping ports or passages 175 having a generally elongated rectangular crosssccrional configuration. It will be noted that these vanes are symmetrically disposed with respect to the axis 165 of the impeller which actually corres onds to the rotational axis of the impeller and the impeller shaft.

It will be noted that each of the pumping vanes has a pressure face which faces in the direction of rotation as indicated by the arrow in FIG. 5, each of the pressure faces of the pumping vanes having a radially extending mid portion 166 substantially midway between the adjacent side surfaces of the pumping vanes, such mid portions lying substantially along a line which passes through the axis 165. In addition, each of the pumping vanes 152 is provided with a central or longitudinal axis aa. It will be noted that the central or longitudinal axes an of each of the pumping means is offset with respect to the rotational axis 165 of the impeller, and in fact, each of the axes an is so disposed that it is tangential to an imaginary circle which has its center positioned on the rotational axis 165 of the impeller. This novel disposition of the pumping vanes is such that even though the vanes are formed along straight lines with flat surfaces, maximum pumping eihciency is preserve Referring now to P16. 6, the disposition of the exeller vanes d is illustrated. The expeliler vanes are six in number as illustrated and are symmetrically positioned about the impeller. The expeller vanes 154, of course, extend from an inner surface 170 of the impeller to the outer surface 143 of the impeller which has already been mentioned. The opposite ends of the expeller vanes are also, of course, open to permit pumping of fluid outwardly by the expeller vanes. The expeller vanes include substantially flat side surfaces 15 and end surfaces 154" which define expeller ports or passages 176 having a generally elongated rectangular cross-sectional configuration.

It will noted that each of the expeller vanes has a pressure face which faces in the direction of rotation as indicated by the arrow in FIG. 6, each of the pressure faces of the expeller vanes having a radially extending mid portion 171 substantially midway between the adjacent side surfaces of the pumping vanes, such mid portions lying substantially along a line which passes through the rotational axis 155 of the impeller. Each of vanes 15 has a central or longitudinal axis bb, each of these axes bb of the expcller vanes being offset with respect to the rotational axis 1.63 of the impeller and being tangential to a circle having its center along the rotational axis 165. In other words, the disposition of the cxpcller vanes 15 is similar to that of the pumping vanes 152 in that in each case the central axes of the vanes are oilset with respect to the rotational axis of the impeller. In this manner, the expeller vanes, although also being formed along straight lines and with fiat surfaces, are enabled to provide a maximum degree of hydraulic efhciency.

Ill: will be noted that the side surfaces 152' of the pumping vanes and 15d of the expeller v..r.es are disposed in substantially parallel planes, these planes extending substantially normally to the axis of rotation of the impeller and impeller shaft. When the apparatus is at rest, or in other words, when the impeller shaft is not rotating, the resilient drive transmitting springs 62 and 53 will urge the impeller shaft to the right into the position shown in FIG. 3 wherein the sealing faces formed on seal rings and 13 2 brought into frictional contact with one another thereby providing a positive mechanical seal which prevents passage of fluid between these two faces.

When the pump is brought up to speed, the centrifugal weights of the control assembly will pivot outwardly thereby causing the impeller shaft to be moved to the left and into the open position shown in FIG. 4- whercin the sealing faces of the seal rings 75 and 192 are spaced from one another. in this manner, while the impelle shaft is rotating, there is no frictional contact between the sealing faces formed on seal ring members '75 and 1&2. Most of the fluid which leaks by the labyrinth means provided between the flange portion 159 of the impeller and the adjacent portion of the liner 111 will in turn be pumped outwardly by the expeller vanes 154. However, a small portion of the fluid may escape this hydraulic seal and pass through the annular passage defined by the sealing surfaces on the seal rings 75 and 192.

The fluid which passes through the aforementioned annular passage will then contact the shaft sleeve 30 and the stationary seal ring housing 162) and thence be carried out of and away from the apparatus through funnel portion 165.

The important thing to note in this connection is the fact that all of the components of the pump apparatus which the fluid may engage not only due to the pumping action of the pump but also including any leakage past the hydraulic seal will only contact components having surfaces formed thereon of a corrosion resistant material. Of course, upon cessation of rotation of the imeller shaft, the centrifugal Weights of the s eed responsive control means will pivot inwardly thereby permitting the spring driving connection 62 and 63 to return the impeller shaft and the associated components to the closed position shown in FIG. 3 such that a mechanical fluid seal is again provided when the pump is at rest.

It is apparent from the foregoing that there is provided a new and novel corrosion resistant centrifugal pump wherein all the parts which come in contact with the pumped fluid are formed of corrosion resistant material. All friction is eliminated between the corrosion resistant components of the apparatus during pumping operations, and in fact no mechanical seals at all are provided while the pump is operating. The construction is sum as to provide maximum strength and rigidity even though relatively brittle corrosion resistant materials are employed. The novel disposition of the pumping and expellcr vanes of the impeller provide maximum hydraulic eiliciency while at the same time the vanes as well as the entire impeller are constructed along straight line flat surfaces which permit ready forming of the impeller. The app;- ratus is furthermore quite simple, compact and inexpensive in construction.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

We claim:

1. A corrosion resistant centrifugal pump comprising a pump housing an impeller shaft rotatably supported within said housing about an axis of rotation, an impeller formed of corrosion resistant hard-to-form material secured to one end portion of said impeller shaft and having both pumping vanes and expeller vancs formed thereon of similar construction, said vanes being defined by surfaces formed along continuous straight lines to facilitate formation of the impeller and each having a longitudinal axis which is offset with respect to said axis of rotation, the side surfaces of said pumping vanes and expeller vanes being disposed in substantially parallel planes, said planes extending substantially normally to said axis of rotation, each of said pumping and expeller vanes including end surfaces extending between said side surfaces to define therewith passages of generally elongated rectangular cross-sectional configuration, one end surface of each of said pumping and expeller vanes defining a pressure face, each of said pressure faces of the pumping and expeller vanes having a radially extending mid portion substantially midway between the adjacent side surfaces of the vanes, such radially extending mid portions lying substantially along a line passing through said axis of rotation, a first sealing means supported by said impeller shaft and connected for rotation therewith, a second sealing means supported by said housing and cooperating with said first sealing means to provide a seal therewith, means for shifting said impeller shaft axially thereof for moving said sealing means away from one another to break the seal therebetween, means normally urging said sealing means into sealing relationship with one another, said sealing means each being formed of corrosion resistant 10 material, the portions of said housing adjacent said impeller being spaced therefrom and also being formed of corrosion resistant material such that the portions of the pumping means which engage the pumped fluid resist corrosion during use.

2. Apparatus as defined in claim 1, wherein said housing includes an inner liner means disposed adjacent said' impeller, said inner liner means being formed of corrosion resistant material, said housing including outer reinforcing means adjacent said inner liner means for adding rigidity and strength to the pump.

3. Apparatus as defined in claim '2, wherein said inner liner means is formed of corrosion resistant material and is formed along straight lines to facilitate formation thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,756,323 Wilfley Apr. 29, 1930 1,986,836 MacNeille Jan. 8, 1935 2,029,333 Miller Feb. 4, 1936 2,107,260 Ihara Feb. 1, 1938 2,433,589 Adams Dec. 30, 1947 2,471,653 Price May 31, 1949 2,571,802 Wilfiey et a1. Oct. 6, 1951 2,835,203 Cliborn May 20, 1958 2,905,093 Raub et al. Sept. 22, 1959 3,037,458 Olmstead et al. June 5, 1962 3,048,384 Sweeney et al. Aug. 7, 1962 FOREIGN PATENTS 552,902 Great Britain Apr. 29, 1943 575,346 Great Britain Feb. 14, 1946 725,507 Germany 1 Sept. 23, 1943 914,214 Germany June 28, 1954 OTHER REFERENCES Publication: Goulds-Pfandler, Glassed Pumps, pages 1, 5-13, July 24, 1958. 

1. A CORROSION RESISTANT CENTRIFUGAL PUMP COMPRISING A PUMP HOUSING AN IMPELLER SHAFT ROTATABLY SUPPORTED WITHIN SAID HOUSING ABOUT AN AXIS OF ROTATION, AN IMPELLER FORMED OF CORROSION RESISTANT HARD-TO-FORM MATERIAL SECURED TO ONE END PORTION OF SAID IMPELLER SHAFT AND HAVING BOTH PUMPING VANES AND EXPELLER VANES FORMED THEREON OF SIMILAR CONSTRUCTION, SAID VANES BEING DEFINED BY SURFACES FORMED ALONG CONTINUOUS STRAIGHT LINES TO FACILITATE FORMATION OF THE IMPELLER AND EACH HAVING A LONGITUDINAL AXIS WHICH IS OFFSET WITH RESPECT TO SAID AXIS OF ROTATION, THE SIDE SURFACES OF SAID PUMPING VANES AND EXPELLER VANES BEING DISPOSED IN SUBSTANTIALLY PARALLEL PLANES, SAID PLANES EXTENDING SUBSTANTIALLY NORMALLY TO SAID AXIS OF ROTATION, EACH OF SAID PUMPING AND EXPELLER VANES INCLUDING END SURFACES EXTENDING BETWEEN SAID SIDE SURFACES TO DEFINE THEREWITH PASSAGES OF GENERALLY ELONGATED RECTANGULAR CROSS-SECTIONAL CONFIGURATION, ONE END SURFACE OF EACH OF SAID PUMPING AND EXPELLER VANES DEFINING A PRESSURE FACE, EACH OF SAID PRESSURE FACES OF THE PUMPING AND EXPELLER VANES HAVING A RADIALLY EXTENDING MID PORTION SUBSTANTIALLY MIDWAY BETWEEN THE ADJACENT SIDE SURFACES OF THE VANES, SUCH RADIALLY EXTENDING MID PORTIONS LYING SUBSTANTIALLY ALONG A LINE PASSING THROUGH SAID AXIS OF ROTATION, A FIRST SEALING MEANS SUPPORTED BY SAID IMPELLER SHAFT AND CONNECTED FOR ROTATION THEREWITH, A SECOND SEALING MEANS SUPPORTED BY SAID HOUSING AND COOPERATING WITH SAID FIRST SEALING MEANS TO PROVIDE A SEAL THEREWITH, MEANS FOR SHIFTING SAID IMPELLER SHAFT AXIALLY THEREOF FOR MOVING SAID SEALING MEANS AWAY FROM ONE ANOTHER TO BREAK THE SEAL THEREBETWEEN, MEANS NORMALLY URGING SAID SEALING MEANS INTO SEALING RELATIONSHIP WITH ONE ANOTHER, SAID SEALING MEANS EACH BEING FORMED OF CORROSION RESISTANT MATERIAL, THE PORTIONS OF SAID HOUSING ADJACENT SAID IMPELLER BEING SPACED THEREFROM AND ALSO BEING FORMED OF CORROSION RESISTANT MATERIAL SUCH THAT THE PORTIONS OF THE PUMPING MEANS WHICH ENGAGE THE PUMPED FLUID RESIST CORROSION DURING USE. 